On Fri, Jun 28, 2013 at 8:56 AM, Adrian Chadd <adr...@freebsd.org> wrote:
> On 28 June 2013 08:37, Alexander Motin <m...@freebsd.org> wrote: > >> Otherwise it may just creep up again after someone does another change > >> in an unrelated part of the kernel. > > > > Big win or small, TAILQ is still heavier then STAILQ, while it is not > needed > > there at all. > > You can't make that assumption. I bet that if both pointers are in the > _same_ cache line, the overhead of maintaining a double linked list is > trivial. No, it's not. A singly-linked SLIST only needs to modify the head of the list and the current element. A doubly-linked LIST needs to modify both the head as well as the old first element, which may not be in cache (and may not be in the same TLB, either). I don't recall exactly what [S]TAILQ touches, but the doubly-linked version still has to modify more entries that are not contiguous. Thanks, matthew _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
